One type of widely used image-forming device forms an electrostatic latent image on a photosensitive member by exposing the photosensitive member to light after applying a charge to the surface thereof, and subsequently develops the latent image by depositing toner thereon. This type of image-forming device may employ means for scanning a laser light beam over the surface of the photosensitive member as exposing means, while another type of exposing means well known in the art is an LED print head comprising a plurality of light-emitting diodes (LEDs).